Chemistry

The use of chemistry in forensic science extends to determining blood alcohol levels, understanding explosives, analyzing fires, studying gunshot residue, and identifying drugs and other controlled substances both pure and from human secretions. Each of these areas contributes to an understanding of the crime and the evidence.

Blood Alcohol

Drugs/Controlled Substances

Explosives

Fire Analysis

Gunshot Residue

Specific Projects

Ion Mobility Spectrometry Trace Drug Detection Devices
Detecting contraband drugs is a high priority for a large number of law enforcement organizations. We support NIST’s work on Ion Mobility Spectrometry (IMS) Trace Drug Detection Devices. IMS is already used throughout the country to detect explosives at airports. The goal of this program is to study how well the IMS method detects drugs and to develop standards for using IMS both through swiped samples and portal detectors.

Current use of IMS to detect drugs has shown deficiencies, such as a high false-positive alarm rate for some drugs and a high false-negative rate (lack of detection) for other drugs. To address these deficiencies, we are:

Studying instruments that law enforcement personnel can use with similar sensitivity to IMS but better selectivity; and

Studying an IMS-based portal detector and two new desktop IMS instruments. For this study, we will:

Work with other areas of NIST to design an experiment with multiple variables for at least two desktop instruments that tests for factors including temperature, humidity, sample preparation, and sample matrix; and

Study solid phase micro-extraction used in conjunction with IMS since this approach has the potential to provide a faster, easier, and more portable method of drug analysis in biological samples than those commonly used today.

Fire Research: Pattern Repeatability
We are also working with the National Institute of Justice to support research into fire patterns, which assist in fire analysis. Additional understanding of fire patterns can help forensic scientists characterize the source of fires based upon the heat release rate, heat flux, plume temperature, and flame height. We supported experiments to examine the repeatability of pre-flashover fire patterns generated by short-duration fires from natural gas, gasoline, and polyurethane foam. We will share the data from these experiments with standards organizations, and it will serve as input data for the Fire Dynamics Simulator/Smokeview, a computational fluid dynamics program that re-creates burn patterns.